Kinetic study of the oxidative dehalogenation of 2,4,6-trichlorophenol catalyzed by chloroperoxidase

A sigmoidal behaviour of chloroperoxidase for the oxidative dehalogenation of 2,4,6-trichlorophenol is reported for the first time. Kinetic data were adjusted to the Hill equation and the kinetic parameters were obtained: n = 1.7 ± 0.2, vmax=(8.8±0.3)×10−5 M min−1vmax=(8.8±0.3)×10−5 M min−1, the pseudo-Michaelis constant Ks* = (8.6 ± 0.5) × 10−5 M, kcat = 677 ± 84 min−1 and the catalytic efficiency = (8.9 ± 0.6) × 106 M−1 min−1. The sigmoidal curve could be related to the cooperative binding of the substrate to the enzyme, so that the binding of the first substrate molecule may help the binding of the second one. Further, both substrate molecules could establish Π–Π interactions between them, which would confer more stability to the system.

Research highlightsThe manuscript highlights the sigmoidal kinetics of the oxidative dechlorination of 2,4,6-trichlorophenol (TCP) in the presence of an oxidant (hydrogen peroxide) catalyzed by the enzyme Chloroperoxidase (CPO) from Caldariomyces fumago. This atypical kinetics was observed for the first time, and the Hill equation was used to fit the kinetic data and to estimate the kinetic parameters.